Objectives: The efficacy of antihypertensive agents can vary in patients. Four to 8 weeks may be required before antihypertensive agents become fully effective. Predicting the efficacy can help agent selection and dose setting. This study determined whether nitroglycerin-induced vasodilation of brachial arteries can predict the antihypertensive action of angiotensin II receptor antagonist.
Methods: Untreated uncomplicated patients with essential hypertension, who gave informed consent, were studied (n = 20, mean age 55 years). Before antihypertensive treatment, nitroglycerin-induced vasodilation of the brachial arteries was measured using a novel method of 15 MHz high-frequency high-frame-rate ultrasound imaging (Hitachi EUB8000). Diameter of the brachial artery at the end-systolic phase was measured before and after 0.3 mg nitroglycerin sublingual spray and percentage vasodilation (%D-N) was calculated. The reduction of mean blood pressure after nitroglycerin (%BP-N) was calculated. Valsartan monotherapy (40-80 mg/day)was administered for 3-6 months (mean 132 days). Reduction of mean blood pressure after valsartan monotherapy (%BP-V) was calculated.
Results: Valsartan decreased systolic blood pressure from 138 +/- 13 to 130 +/- 17 mmHg, and diastolic blood pressure from 83 +/- 11 to 78 +/- 11 mmHg (p < 0.05). %D-N was correlated closely with %BP-V (r = - 0.70, p < 0.001). %BP-N had no correlation with %BP-V (r = 0.13, p = 0.58).
Conclusions: Direct vasodilatory action of nitroglycerin on vascular smooth muscle cells may predict the chronic antihypertensive effect of angiotensin II receptor antagonist.